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Non-Minimum Phase IRs

Discussion in 'Axe-Fx III Discussion' started by FractalAudio, Jan 3, 2019.

  1. shatteredsquare

    shatteredsquare
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    i only tried two ways so far, 44.1k 16 bit and 96k 24 bit...the results i got with what Axe Manage Cabs ended up giving to the AxeFx3 is drastically different (96k sounding like a CD, 44.1k sounding like a cassette tape). Maybe the bit rate had more to do with it than anything, I'm not savvy on the specifics of the conversion process.

    I haven't tried any other resolutions yet, since the AFX3 is locked at 48k, maybe anything above that just gets down-sampled and doesn't make a difference. I await my correction!
     
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  2. DLC86

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    That's correct
     
  3. shatteredsquare

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    what about different bit rate at the same sample rate? At 48k (or above) do you get a different quality result using 48k 16 bit vs 48k 24 bit?
     
  4. DLC86

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    I think so, axe is 24 bit
     
  5. FractalAudio

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    The Axe-Fx III uses 32-bit floating point so that would be the best, if available. If not, 24 bits is fine. 48K would be my recommendation as any other frequency will require SRC.
     
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  6. Perdikament

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    Just out of curiosity, are all SRC’s created equally? Well I guess for our purposes here would it make any difference in the quality of the conversion between AxeEdit or CabLab?
     
  7. FractalAudio

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    No they aren't. I wrote the one that's used in our products and it performs well but it's better not to convert if you don't have to.
     
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  8. DLC86

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    Don't IR producers create lower sample rate files by SRC anyway? Or they actually capture each IR several times for every SR?
     
  9. FractalAudio

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    I don't know. Some might actually up-convert.

    The best way to capture an IR is to use the Axe-Fx itself. It employs several tricks that result in higher-quality data.
     
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  10. shatteredsquare

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    i was wondering that, if it's locked at 48k it doesn't make sense to feed it anything higher. i'll re-import at 48k and see if it makes any audible difference. maybe it will just take less time for the script to run.
     
  11. rodzimguitar68

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    Cliff,

    When you do this, are you literally going to replace the factory banks with them, or do you mean, you will have a zip file containing the factory cabs in non-min-phase, and we will be able to load them into user slots?

    Thanks,

    Rod
     
  12. DLC86

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    I think the former would be more practical if coupled with an MPT switch in the cab block.
     
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  13. shatteredsquare

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    I think (right now) all IR waveform processing is done prior to import, when the wav files get converted to sysex data
     
  14. DLC86

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    Yes, that was a "wish"
     
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  15. shatteredsquare

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    wonder since the AFX3 uses syx data for IRs, how cool it would be to tie metadata into them, so when you load a V30 IR the speaker page loads up V30 impedance curve. Vacation time over :( so no more days on end time to dabble but I've been thinking about going through each amp block with default values and consolidating a list of the speaker page settings for each, to compare how V30 settings sound with a V30 IR vs V30 settings with a G12T-75 IR. Never actually took the time yet to do that. It would be awesome to have a drop down list in the speaker page of different speaker types to load up quick.
     
  16. DLC86

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    The impedance curve you see in speakers' datasheets is measured in free air, when you mount that speaker inside a cab its curve changes depending on various factors such as enclosure internal volume, size, type of construction (open, closed, ported), etc..

    So creating settings to replicate the impedance curve of a V30 would be pointless, you actually need the curve of a V30 inside the cab it was in when the IR was captured.

    Metadata for that in the syx file is a nice idea though ;)
     
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  17. shatteredsquare

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    I meant go through the amps that were no doubt modeled up with V30s (Recto) and copy those speaker settings down, so when I load up an AC 30 and send it screaming through the same 4x12 IR, put those recto speaker settings (V30) into the AC30 speaker page and see how it do, see if the AC30 looking at a V30 impedance curve combined with a V30 IR frequency response gives a giggle
     
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  18. Chronos

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    Just set dephase to .01 and it will automatically turn any raw IR to be MPT as things are right now
     
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  19. DLC86

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    Yeah, discovered that yesterday in another thread.
     
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  20. Chronos

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    Dang. Late to the thread and late to giving a useful tip. Didn't think it was something too many people would have discovered. I use it all the time when mixing raw IR's that I have on my unit
     
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